Many people, even those with otherwise good vision, have minor vision deficiencies that fall under the category of non-conventional refractive error that prevent them from achieving the best visual acuity possible. Unlike conventional refractive error, i.e. “near-sightedness” or “far-sightedness” and other types of problems usually addressed in persons with corrected vision, the impact of unconventional refractive error, such as higher order aberrations, may even be difficult for an individual to perceive until it has been identified, measured and corrected during an eye exam and the individual has an opportunity to realize the increased visual acuity that accompanies correction of these errors.
The effect of higher order aberrations may vary depending on environmental conditions, such as distance from an object being viewed or the size of the pupil, which fluctuates based on the distance viewed and the amount of ambient light entering the pupil. Thus, a lens that has a fixed correction for higher order aberrations may still not provide an individual a proper correction except under certain conditions.